Electric operator for overload clutches



Aug. 1, 1950 R. HODGES EIAL ELECTRIC OPERATOR FOR OVERLOAD-CLUTCHES Original Filed July 17, 1942 3 Sheets-Sheet 1 IN VEN TOR.

HODGES RlLPH JOHN H. KLASEY M Aug. 1, 1950 R. HODGES ETAL ELECTRIC OPERATOR FOR OVERLOAD CLUTCHES 3 Sheets-Sheet 2 Original Filed July 1'7, 1942 6 0T. Rag mm mi 8 w o 2 0 QM \NT S ww \NQ R J wm H8 74 Nm mm 7 INVENTOR.

RALPH HODGES BY JOHN H. KLASEY Patented Aug. 1, 1950 ELECTRIC OPERATOR FOR OVERLOAD CLUTCHES Ralph Hodges, Belleville, Ill., and John H. Klascy, St. Louis, Mo, assignors to Carter Carburetor Corporation, St. Louis, M0., a corporation of Delaware Original application Iuly 17, 3.942, Serial No. 451,268. Divided and this application August 23, 1944, Serial No. 550,700

The present invention relates to overload clutch devices, particularly adapted for use with machine tools. This application is a division of our copending application Serial No. 451,268 filed July 17, 1942, now Patent No. 2,395,121.

Automatic machine tools, such as that illustrated in the above mentioned application, require some sort of device which will protect the machine and tools from damage in case the operation is impeded or stopped by an overload. In overload clutches as commonly used, the clutch part becomes disengaged at such time, but rotation thereof continues resulting in annoying chattering and possible damage to the clutch teeth.

It is an object of the present invention to pro vide a safety device of the overload clutch type in which the application of power to the working parts of the machine is dependent upon operating contact of the clutch part and, in which, separation of the clutch parts, as by an overload, immedi-ately stops the application of power to the machine.

This object, and other more detailed objects hereafter appearing, are attained by the device illustrated in the accompanying drawings in which Fig. 1 is a side view illustrating a drilling head unit having the novel overload clutch applied thereto, parts being broken away for clearer illustration.

Fig. 2 is an end view of the unit.

Fig. 3 is a top view of the unit.

Fig. 4 is a detail. vertical section taken approximately on the section line 4- of Fig. 1.

Fig. 5 is a section taken substantially on the broken section line 55 of Fig. 1.

Fig. 6 is a wiring diagram for the clutch and tool unit.

The operating mechanism of the unit is enclosed in a casing including side plates 28 and 20, end plates 2! and 22, bottom plate 20, and top plate i9. Longitudinally slidable in the lower part of the casing are telescoping sleeve and spindle members, the left hand extremities there-' of being shown at 3% and 39. Spindle 39 is supported in a quill of which the extremity is shown at 38. The right hand portion of the spindle is fluted, as shown at 39a in Fig. 4, and received within and keyed to rotate with a hollow shaft 42, the fiuting of the spindle permitting relative longitudinal movement thereof within hollow shaft 42, the latter being threaded to form a worm, which meshes with a worm gear 85. Gear 85 is keyed to a sleeve I2 I' supported in bear- 7 Claims. (Cl. 192-40) ings 88 and 89 and received on a transverse shaft 3?, supported in bearings 90 and 9|. Bearing 98 is carried in a plug I21 bolted in right hand side plate 29 (Fig. 4) A pinion 92 is keyed to the left hand end of shaft 8! and transmits force to reciprocate the sleeve member and spindle longitudinally, according to predetermined operating cycles, through gear trains including gears 93, so, 93, large gears I03 and IE9 having cam grooves on their inner surfaces, as at I05, and cam follower levers 59 and 69, the latter having a roller ill operating in groove Hi5 of the gear Hi3. Gears 93 and 9? are mounted on a cross shaft 9e supported in bearings 95 and 95. For more complete disclosure of the operating mechanism of thetool unit, reference is made to the above mentioned copending application.

The advancing and retracting mechanisms are driven from a motor shaft (not shown) operativeiy connected to gear l'l secured to the outer end of the hollow shait ii and through an overload clutch arrangement which constitutes the present invention. The end of shaft Bl opposite pinion 92 is fluted and receives thereon a toothed clutching plate H33, for rotation therewith but capable of longitudinal movement therealong. The adjacent end of sleeve 86 is enlarged, as at it I, and is provided with tapered clutching teeth to cooperate with opposing teeth on plate i213. A collar I22 is loosely received on clutch plate 123 and is apertured at !23 for receiving pins 324 on clutch yoke 525. The outer face of clutch plate 121! is roughed, as at H16 (Fig. l) for braking engagement with the roughened inner face of a fixed plug I21 seated in side plate 2.

Yoke 525 is secured to a vertical shaft H28 at upper end oi which is rigidly fastened a bell crank H29. One arm Hits of this bell crank is connected through multiplying leverage I38 and Hi to a stem [32 on the core 533 of a solenoid lt i mountedon a bracket lI-lii on top plate :9. When solenoid 53:3 is energized, clutch parts I20 and |2l are caused to engage so that power is transmitted from gear 85 and worm 42 to the tool advancing and retracting mechanisms.

Also mounted on the top plate of the framing is a switch housing I36 from which projects the clutch safety limit switch operator 531 in position to be actuated by the short arm 52% of bell crank Hi9, and the clutch overload cut-off switch operator I33 in position to be actuated by a depending pin I39 on longer arm l29a of bell crank I29. Bell crank 129 is constantly urged clock-- wise by a, coiled tension spring I40 so that when solenoid I34 is ole-energized, switch operator pin I31 is moved into the switch housing to close the safety switch, and switch operator pin I38 is projected outwardly of the housing for opening the cut-out switch.

Additional switch devices in housings MI and IE2 have, respectively, switch operating shafts M3 and I35 with cranks I45 and I45 thereon carrying adjusting tappets Hi1 and [it which extend below guides, as at 558 in topplate I9of the framing, in position to be engaged and urged upwardly by the upper extremities of the cam follower levers, one being shown at 59in Fig. 1, when the tool carrying members operated'thereby are in their retracted positions.

A bracket MI is bolted to a block I52 projecting above the framing top plate and loosely receives a vertical shaft 553. A clutch release hane die I54 is secured to the upper extremity of this shaft and a cam I55 is rigid with the shaft below bracket I5i and aligned with arm I29!) of bell crank Manual rotation of handle I54. and cam I55 causes a high point on the cam to engage and rotate the bell crank shaft I20, and clutch yoke 525 just sufficiently to move clutch plate i to a neutral position between brake plug I21 and clutch sleeve face I2I. When the overload clutch is engaged and the driving motor energized, the sleeve member, of which one extremity is indicated at 340. and the quill and spindle member 39, are jointly advanced forward, and retracted to the rest positions thereof in operative cycles as determined by the feeding mechanisi The diagram in Fig. 6 illustrates the wiring arrangement of the machine head unit when used in a multi-station drilling machine having an indexing work support table. Corresponding parts appearing in the previous figures are given similar designating numerals for reference. The power lines for the unit motor are indicated at I90, three wires being provided for three phase current. The power circuit for the indexing table is shown at I9I and includes a manual indexing button I92 to be pushed by the operator to initiate indexing movement of the table and the correlated cycles of the machine head units. Circuit I9I breaks through normally open clutch safety switch I361; in housing I36 and the normally open contacts I4 Ia of spindle return switch MI and Hi2a of sleeve return switch I42, the latter being two contact switches.

For operating the overload clutch to produce the advancing and retracting cycles of the spindle and sleeve members, a lead I93 from one of the power lines breaks through a switch I94 which is closed in response to locking of the indexing table in a working position, and the coil of a time delay relay I95 and thence by wire I96 to the other power line. Relay I95 is of such character as to automatically open after being closed;

a short time. This relay controls the coil of a magnetic switch I91, one such magnetic switch similarly controlled being provided for each machining head unit. The movable contacts I98 A causes rotation of the train of gears which starts same time, closes switch I362) by engagement of actuating plunger I38 by pin I39 carried by the long arm of the bell crank.

As the feed mechanism starts to operate, switch actuator pins I41 and I48 are released by being disengaged from cam follower levers 59 and 69, permitting reversing of switch contacts I4 Ia and I42a, opening the indexing table circuit I9I and closing contacts MI!) and I421). A second energizing circuit for clutch holding solenoid I 34 is provided by a lead 203 breaking through switch I421), a lead 204 to the power line, and a lead 205 breaking through clutch overload switch [36b and spindle return switch I 4 lb to the other power line.

Thus, if the indexing table is in a working position and both the sleeve and quill are in their rest positions, switches I94, I36a, I4Ia, and I42a will be closed and the operator can initiate the operating cycle by merely pressing indexing button I92. Time relay I and unit control magnetic switch I91 are then closed so as to cause engagement of the overload clutch and start longitudinal reciprocation of the sleeve and spindle members. Initial operation of the feeding mechanism is accompanied by closing of switches I362), I4Ib and I421) and completion of the second circuit 203, 205 for energizing the clutch magnet I34. After a short time interval, the relay I 95 automatically opens. Thereafter, in case an overload should cause separation of clutch elements I29 and I2I, switch I361), which is a micro-switch, will be immediately opened so as to deenergize clutch holding solenoid I34 and stop the reciprocation of the spindle and sleeve members. This eliminates the chattering of the clutch members, which would otherwise occur if holding force were continuously applied to the clutch through solenoid I34 until the operator has stopped the machinery. Damage to the clutch and other parts is thus avoided as is the very annoying chattering noise.

The invention may be modified in various respects as will occur to those skilled in the art and the exclusive use of all such modifications as come within the scope of the appended claims is contemplated.

We claim:

1. In combination with driving and driven members, an overload clutch therebetween, a magnetic device to engage said clutch, an electrical circuit for said magnetic device including an element which automatically opens said circuit shortly after it is closed to engage said clutch, and. an additional circuit for said device to cause the same to apply yielding force to hold saio clutch in engagement dependent upon maintenance of said clutch in engagement.

2. In combination with driving and driven members, an overload clutch therebetween, means to engage said clutch and automatically rendered inoperative to hold said clutch in engagement after a time interval, magnetic means to yieldingly hold said clutch in engagement, and a power circuit for said magnetic means including a micro-switch which is closed automatically and only when said clutch is engaged.

3. In combination with driving and driven members, an overload clutch therebetween, magnetic means to engage said clutch and hold the same in engagement including a first power circuit with a switch which is automatically opened shortly after closing of said circuit to engage said clutch, a second power circuit with a micro switch which is closed only when said clutch is in engagement, means to energize said first power circuit dependent upon the positioning of said driven member in a predetermined rest position, and means for energizing said second circuit dependent upon maintenance of said clutch in engagement.

4. In combination with a driving member and a driven member subject to cyclical movement to and from a rest position, an overload clutch between said driving and driven members, means to engage said clutch dependent upon said cyclically driven member being in its rest position, said engaging means being constructed and arranged to become inefiective to hold said clutch in engagement after a time interval, and additional means rendered operative upon engagement of said cltuch to hold said clutch in engagement.

5. In combination with a driving member and a cyclically moving driven member, an overload clutch therebetween, means to initially engage said clutch dependent upon said driven member being in a predetermined rest position, and means to apply yielding force to hold said clutch engaged dependent both upon said driven member being away from said rest position and the maintenance of said clutch engaged.

6. In combination with driving and driven members, an overload clutch therebetween, me-

chanical means operative to engage said clutch, a magnetic device for operating said mechanical means, an electric circuit for said magnetic device including an element which automatically opens said circuit shortly after it is closed to operate said mechanical means to engage said clutch, and an additional electric circuit for said magnetic device for operating said mechanical means to apply yielding force to hold said clutch in engagement dependent upon maintenance of said clutch in engagement.

7. In combination with a driving member and a cyclically moving driven member, an overload clutch therebetween, mechanism including a bell crank operative to engage said clutch, means for operating said bell crank to initially engage: said clutch dependent upon said driven member being in a predetermined rest position, and means for operating said bell crank to apply yielding force to hold said clutch in engagement dependent both upon said driven member being away from said rest position and also upon the maintenance of said clutch in engagement.

RALPH HODGES.

JOHN H. KLASEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,491,426 Schunemann Apr. 22, 1924 1,678,634 Chandler July 31,. 1928 1,850,299 Watson Mar. 22, 1932 2,068,260 Biggert, Jr. Jan. 19, 1937 

